Question

Why is it conceptually hard for us to imagine why modern cells may have directly arisen as we see today?

1) RNA formation depends directly or indirectly upon DNA and RNA and protein
2) Protein synthesis directly or indirectly depends upon DNA, RNA and proteins
3) DNA replication directly or indirectly depends upon DNA, RNA and protein
4) All of the three positive options are true, so all of these evolving at once seems unlikely
5) None of the statements are correct

Answer 1

Conceptual difficulty in imagining cells arising directly as we see them today is due to the interdependency of DNA, RNA, and proteins, creating a 'chicken and egg' problem. The RNA world hypothesis suggests that RNA, being able to store information and catalyze reactions, could be the precursor to DNA and proteins.

Step-by-step explanation:

It is conceptually hard for us to imagine modern cells directly arising as we see them today because of the interdependent nature of the main biomolecules in cellular function: DNA, RNA, and proteins. Each of these biomolecules relies on the others to carry out its functions:

• RNA formation depends directly or indirectly upon DNA, and also RNA acts as a catalyst and structure in protein synthesis.
• Protein synthesis depends directly or indirectly upon the genetic information contained in DNA, the mRNA transcript, and existing proteins as enzymes and structural components of ribosomes.
• DNA replication depends directly or indirectly upon existing DNA as a template, RNA molecules like primers, and proteins that act as enzymes.

This creates a "chicken and egg" problem: proteins are needed to synthesize and transcribe DNA, but DNA is required to code for proteins. The RNA world hypothesis proposes that RNA, with its ability to both hold genetic information and catalyze chemical reactions, could be the original macromolecule that predates both DNA and proteins, thus potentially solving this conundrum.